Relay Curve Selection Approach for Microgrid Optimal Protection

tohid soleymani aghdam, Hossein Kazemi Karegar

Abstract

Islanded and grid-connected are two working modes for microgrids, which they impose some challenges on overcurrent protection system. Microgrid Short Circuit (SC) level is different in both modes which causes maloperation of relays. Therefore, a new idea, relay, or method is necessary to solve this problem. This paper proposes a curve optimization approach for microgrid protection. Over Current Relays (OCRs) have different kinds, depended on their parameters like standard inverse and extremely inverse. SC variation in two modes of microgrid can be compensated by appropriate relay curve selection. In this paper, OCR curve optimization and selection is proposed for better protection coordination and microgrid protection. A hybrid Genetic Algorithm (GA) and linear programming method (LP) is also used for finding the optimal settings and curve of relays. Proposed method is applied to Canadian distribution benchmark and modified IEEE 14 bus. The results indicate that the OCR curve selection is efficient tool for microgrid protection coordination and fast fault detection..